package my.reflection;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

import static java.lang.System.out;

enum Spy {BLACK, WHITE}

/**
 * $ java FieldModifierSpy my.reflection.FieldModifySpy volatile
 * $ java FieldModifierSpy my.reflection.Spy public
 * $ java FieldModifierSpy my.reflection.FieldModifySpy\$Inner final
 * $ java FieldModifierSpy my.reflection.Spy private static final
 */
public class FieldModifySpy {
    volatile int share;
    int instance;

    class inner {
    }

    public static void main(String[] args) {
        try {
            Class<?> c = Class.forName(args[0]);
            int searchMods = 0x0;
            for (int i = 0; i < args.length; i++) {
                searchMods |= modifierFromString(args[i]);
            }
            Field[] fids = c.getDeclaredFields();
            out.format("Fields in Class '%s' containing modifiers: %s%n",
                    c.getName(),
                    Modifier.toString(searchMods));
            boolean found = false;
            for (Field f : fids) {
                int foundMods = f.getModifiers();
                // Require all of the requsted modfieers to be present
                if ((foundMods & searchMods) == searchMods) {
                    out.format("%-8s[synthetic=%-5b enum_constant =%-5b]%n",
                            f.getName(), f.isSynthetic(),
                            f.isEnumConstant());
                    found = true;
                }
            }

            if (!found) {
                out.format("No matching fields%n");
            }

            // production code should handle this exception more gracefully
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    private static int modifierFromString(String s) {
        int m = 0x0;
        if ("public".equals(s)) m |= Modifier.PUBLIC;
        else if ("protected".equals(s)) m |= Modifier.PROTECTED;
        else if ("private".equals(s)) m |= Modifier.PRIVATE;
        else if ("static".equals(s)) m |= Modifier.STATIC;
        else if ("final".equals(s)) m |= Modifier.FINAL;
        else if ("transient".equals(s)) m |= Modifier.TRANSIENT;
        else if ("volatile".equals(s)) m |= Modifier.VOLATILE;
        return m;
    }

}
